This invention relates to seat assemblies with pivotally mounted back rests and particularly to seat assemblies that have different pivots at different heights for supporting back rests.
In certain types of vehicles in which the seat assemblies are used, the back rests must be folded compactly over the seat cushions to allow access to adjacent equipments. Seat assemblies may have their back rests supported on only one pair of pivots on a single axis of rotation for tilting the back rests and for folding the back rests over their seat cushions. Locking means connected to the back rests provide different degrees of adjustable tilt to suit the occupants of the seat assemblies.
To obtain maximum comfort at various degrees of tilt, the transverse axis about which a back rest of a seat assembly is to be rotated for tilt should be approximately at the height of the pelvis of an occupant of the seat assembly such that for different degrees of tilt, the distance from that portion of the back rest adjacent the pelvis to the upper front edge of the seat cushion remains constant. However, if the back rest were to be folded on pivots at this height, the seat assembly would not be folded as compactly as desired because the entire back rest would be positioned horizontally at a level above the seat cushion, and the edge of the back rest that is normally the lower edge would extend back of the seat cushion.